1. Technical Field
The present invention relates to a composition for injection molding, a sintered compact, and a method for producing a sintered compact.
2. Related Art
A powder metallurgy process for producing a metal product by sintering a molded body containing a metal powder has been widely used in many industrial fields recently because a near net shape sintered compact can be obtained using the process. Further, a ceramic powder can be used in place of a metal powder. There are many methods for producing a molded body (molding methods), however, a powder injection molding method in which an inorganic powder and an organic binder are mixed and kneaded, and injection molding is performed using the resulting kneaded material (compound) is known. A molded body produced by such a powder injection molding method is then subjected to a degreasing treatment to remove the organic binder, followed by firing, whereby a metal product or a ceramic product in a desired shape is obtained.
In such a powder injection molding method, it is necessary to select an appropriate organic binder according to various purposes, for example, for the purpose of imparting shape retainability to the molded body.
For example, JP-A-2008-75153 discloses, as an organic binder to be used in a powder injection molding method, a polyacetal resin, a polystyrene, a polyolefin, a higher fatty acid, and the like.
However, in the case of molding into a complicated shape, unless the shape retainability of the molded body is sufficiently high when degreasing, it is difficult to maintain the shape of the molded body when degreasing and sintering as it is immediately after molding, and therefore, deformation, chipping, or the like occurs which deteriorates the dimensional accuracy of a sintered compact. Due to this, it is desirable to further increase the shape retainability when degreasing.